downgrading 16.09.04 to 16.06.07 and license issue

[SparkJiang05363]

history story:I tried to upgraded the IOS version from 16.03.07 to 16.09.04 successfully，but I overlooked an issue about the license：

 License Authorization:
Status: EVAL MODE
Evaluation Period Remaining: 51 days, 8 hours, 14 minutes, 6 seconds

Cisco recommend me get the smart license,but need PAK file.

my question is:

I can't get the pak file(I may lost this file and can't get pak from vendor),

After the downgrade to 16.06.07, would the switch get the ip services license in order to run OSPF on the fly? Or do I need to enter the following command in order to be activate ip service licenses?

license right-to-use activate ipservices acceptEULA

this is my understanding：

step 1:downgrading 16.09.04 to 16.06.07.

step 2:license right-to-use activate ipservices acceptEULA

then the license issue should be solved?

[Leo Laohoo]

If you activate the PAK file in 16.6.X and then go back up to 16.9.X (and later), your licenses will go back to "0". The appliance will "ignore" the license PAK and will try to contact the "mothership" (aka Smart Licensing Server).
If using 16.9.X, configure Cisco Smart License (CSL).