Also have your serial number handy and if the LR 5 serial is for an upgrade version have a previous version serial number on hand also.
Thanks for the suggestion. I'll try next weekend and I guess, as you say, it will get me back to where I was. Still have the doubt however if I can also do it the other way around: upgrade to LR 6, but with the issue of having a license from one country and now living in another. Thanks a lot in any case.
You can upgrade to LR 6, stand alone, Upgrade one time cost, or subscribe to the Photographers plan for $9.99 US a month (Exchange rate may be much different) and get both the newest versions of LR CC and Photoshop CC.
Go here to buy the Upgrade of LR 6.
After clicking the BUY button you can select Upgrade which will lower the cost.
Buying LR 6 while in a different country that where you bought LR 5 doesn't matter. But you will need the serial number from LR or any other previous version to use the Upgrade serial number for LR 6.