I've heard from a few people how difficult it is to manage skill license and keep track of them, so I've created a list that should help out.
In order to determine what a skill license actually does when looking at it, ignore the first 5 digits of the number and look at the last 3 digits. Technically it's the last 4, but if you look at several licenses you'll noticed all of them have a 0 in the same spot there. For example, whenever you start the game you start with some random licenses already in your inventory, and there is always at least one copy of 'License 45330371'. We look at the '371' part, look at where that is in this list, and find that it's a single-target healing skill.
Also, if something has 'STAT based', that means it bases the numerical power of the skill off of the listed stat of the user, unless otherwise stated.
101-110: Slash dmg, STR based.
112-121: Bludgeon dmg, STR based.
123-132: Pierce dmg, AGI based.
134-143: Fire dmg, LOG based.
145-154: Cold dmg, LOG based.
156-165: Toxic dmg, AGI based.
167-176: Acid dmg, AGI based.
178-187: Energy dmg, LOG based.
189-198: Explosive dmg, STR based.
200-209: Holy dmg, DEV based.
211-220: Profane dmg, DEV based.
222-231: Order dmg, ARM based.
233-242: Chaos dmg.
244-253: Space dmg, SPD based.
255-264: Time dmg, LOG based.
266-275: Non dmg, ((STR+AGI+LOG+DEV)/4) based.
278-279: STR buffs.
280-281: AGI buffs.
282-283: LOG buffs.
284-285: DEV buffs.
286-287: SPD buffs.
288-289: ARM buffs.
290-291: Hp Regen buffs.
292-293: Mp Regen buffs.
294-295: Mp Cost buffs.
296-297: Lifesteal buffs.
298-299: Manasteal buffs.
300-301: Recovery buffs.
302-303: Critical buffs.
304-305: Accuracy buffs.
306-307: Evasion buffs.
308-322: Elemental Resist buffs.
324-325: STR debuffs.
326-327: AGI debuffs.
328-329: LOG debuffs.
330-331: DEV debuffs.
332-333: SPD debuffs.
334-335: ARM debuffs.
336-337: Hp Regen debuffs.
338-339: Mp Regen debuffs.
340-341: Mp Cost debuffs.
342-343: Lifesteal debuffs.
344-345: Manasteal debuffs.
346-347: Recovery debuffs.
348-349: Critical debuffs.
350-351: Accuracy debuffs.
352-353: Evasion debuffs.
354-368: Elemental Resist debuffs.
371-374: Single target heal, DEV based.
375-377: Party-wide heal, DEV based.
378-380: Revive, target's Max HP based.
383-384: Party-wide heal & debuff cleanse, DEV based.
385: Removes buffs on all enemies.
386: Heal over time, DEV based.
387: Damage over time, STR based.
388: Damage over time, AGI based.
389: Damage over time, LOG based.
390: Damage over time, DEV based.
391: 90% damage reduction for the next 1 hit.
392: Reduces your chance to be targeted.
393: Increases your chance to be targeted.
394: Chaos damage heals user's Hp for 50% of dmg dealt, LOG based.
401-418: Passive skills.Hope these guidelines help!